Light: Mirrors and Lenses

What Are Spherical Mirrors?

Mirrors Beyond the Flat Surface

You've been looking into plane mirrors your whole life. They show you a reflection that is upright, the same size as you, and seems to be as far behind the mirror as you are in front of it. But what happens when the mirror's surface isn't flat?

Think about the last time you saw your reflection in a shiny new steel spoon. Did you look the same as you do in your bathroom mirror? Probably not! The curved surfaces of objects like spoons act like a special kind of mirror, creating images that are stretched, shrunken, or even flipped upside down. These are our first clue into the fascinating world of spherical mirrors.

Activity: Your Face in a Spoon

Let's do a simple experiment that you can try right now in your kitchen. This will help you experience the two main types of spherical mirrors firsthand.

1. Find a shiny steel spoon. Make sure it's clean and reflective.
2. Look into the inner, curved-in side. This is the side you scoop soup with. Hold it close to your face. What do you see? Is your image upright or upside down (inverted)? Is it bigger or smaller than your face?
3. Slowly move the spoon away from your face while looking at your reflection. Observe how the image changes.
4. Now, flip the spoon over. Look at the outer, bulging side.
5. Observe your image again. Hold it close and then move it away. How is this image different from the one you saw on the inner side?

You would have noticed that the inner, hollow part of the spoon shows an inverted (upside-down) image when it's a bit far. The outer, bulging part, however, always shows an erect (upright) but smaller image of your face.

{{VISUAL: photo: A side-by-side comparison of a person's reflection in the inner (concave) and outer (convex) surface of a shiny spoon, clearly showing one image inverted and the other erect and smaller.}}

This simple spoon acts as two types of curved mirrors in one!

What Are Spherical Mirrors?

The spoon's surface is a curved reflector. A spherical mirror is a mirror whose reflecting surface is a part of a hollow sphere. Imagine a hollow glass ball. If you were to cut a piece out of it and coat one side to make it reflective, you would have a spherical mirror.

{{KEY: type=definition | title=Spherical Mirror | text=A mirror whose reflecting surface is a part of a hollow sphere. The reflecting surface can be curved either inwards or outwards.}}

There are two main types of spherical mirrors, defined by which side of the "sphere-slice" is reflective.

1. Concave Mirrors

A spherical mirror whose reflecting surface is curved inwards is called a concave mirror. Think of the inside of a cave – it curves inwards, away from you. The inner, scooping surface of the spoon acts like a concave mirror.

{{KEY: type=definition | title=Concave Mirror | text=A spherical mirror with a reflecting surface that is curved inwards, away from the incident light.}}

In diagrams, we show a concave mirror with the reflective surface on the left and shaded lines on the right to indicate the non-reflective, coated side.

2. Convex Mirrors

A spherical mirror whose reflecting surface is curved outwards, or bulges out, is called a convex mirror. The back of the spoon is a great example of a convex surface.

{{KEY: type=definition | title=Convex Mirror | text=A spherical mirror with a reflecting surface that is curved outwards, towards the incident light.}}

Diagrams for convex mirrors show the curve bulging towards the left (the reflective side), with the shading on the inner curve.

{{VISUAL: diagram: A clear illustration showing a hollow sphere. A section is cut out to form two mirrors: a concave mirror (coating on the outer surface, reflection on the inner) and a convex mirror (coating on the inner surface, reflection on the outer).}}

{{ZOOM: title=How Are Mirrors Really Made? | text=While we imagine mirrors as slices of a perfect sphere, they aren't actually made that way. Instead, manufacturers take a flat piece of glass and carefully grind and polish it to get the precise desired curve. Then, a thin, reflective layer of a metal like aluminium or silver is applied to one side.}}

Characteristics of Images

So, we know these mirrors look different, but as our spoon experiment showed, the real difference is in the images they form. A plane mirror is predictable: it always forms an erect image of the same size. Spherical mirrors are much more dynamic.

Let's summarize the initial findings from observing an object (like a small toy) placed in front of these mirrors.

Notice the key differences:

• A convex mirror always forms an erect and diminished (smaller) image, no matter where the object is.
• A concave mirror is versatile. It can form an enlarged, erect image (like a makeup or shaving mirror) when you're close, but it forms an inverted image when you move far away.

{{KEY: type=points | title=Image Formation Summary | text=- A convex mirror always forms an erect and diminished image.

• A concave mirror can form both erect/enlarged images (object close) and inverted images (object far).
• A plane mirror always forms an erect, same-sized image.
• All three types of mirrors show lateral inversion.}}

Real-World Applications

You can spot these mirrors all around you if you know where to look!

• Concave Mirrors: The reflector behind the bulb in a torch or car headlight is concave. It helps to project a powerful, parallel beam of light. Dentists use a small concave mirror to get an enlarged, magnified view of your teeth.

• Convex Mirrors: These are often used as rear-view mirrors in vehicles and as security mirrors in shops. Why? Because they always show an erect image and provide a wider field of view, allowing drivers or security staff to see more of the area behind them.

What Are the Characteristics of Images Formed by Spherical Mirrors?

What Are the Characteristics of Images Formed by Spherical Mirrors?

In the previous section, we learned to identify spherical mirrors by their shape: concave mirrors curve inwards, like the inside of a spoon, while convex mirrors bulge outwards. But how do these curved surfaces affect the images we see in them? They are quite different from the simple reflection in a plane mirror.

Let's explore this by imagining an activity. If you place a small object, like a toy, very close to both a concave and a convex mirror, you'll immediately notice some striking differences.

Image Formation by a Concave Mirror

When you bring an object very close to a concave mirror, you'll see an image that is erect (upright) and larger than the object. This magnified view is why concave mirrors are often called "magnifying mirrors."

However, the magic of a concave mirror unfolds as you move the object away from it.

• As the object moves farther, the image suddenly flips! It becomes inverted (upside down).
• The size also changes. As it moves away, the inverted image is initially large, but then it gets smaller and smaller the farther you go.

{{KEY: type=points | title=Image Formed by a Concave Mirror | text=- When the object is close, the image is erect and enlarged.

• When the object is moved farther away, the image becomes inverted.
• The size of the image changes with the object's distance.}}

This changing nature of the image—from erect to inverted, and from enlarged to smaller—is a unique characteristic of concave mirrors.

Image Formation by a Convex Mirror

A convex mirror behaves much more predictably. No matter where you place the object, close or far, the image formed by a convex mirror is always:

• Erect (upright)
• Diminished (smaller than the object)

As you move the object away from a convex mirror, the erect image simply gets even smaller, but it never flips or becomes larger than the object.

{{VISUAL: diagram: Comparison of image formation in concave and convex mirrors when an object (like a toy) is placed very close to them, showing the concave mirror forming an enlarged, erect image and the convex mirror forming a diminished, erect image.}}

One more important point: just like a plane mirror, both concave and convex mirrors show lateral inversion. This means the right side of the object appears as the left side of the image, and vice-versa.

Comparing Plane, Concave, and Convex Mirrors

Let's summarize the key differences in a table. This is a very useful way to remember the properties for your exams.

{{KEY: type=exam | title=How to Identify Mirrors | text=In exams, you might be asked to identify a mirror based on the image it forms. Remember: an always-diminished, erect image means it's a convex mirror. An image that can be enlarged or inverted is formed by a concave mirror. An image of the same size is from a plane mirror.}}

Where Do We Use Spherical Mirrors?

The unique properties of concave and convex mirrors make them incredibly useful in our daily lives. You've probably used them today without even realizing it!

Uses of Concave Mirrors

The ability of concave mirrors to magnify objects or focus light into a powerful beam is key to their applications.

• Torches and Headlights: The reflector behind the bulb in a torch, car headlight, or scooter headlight is a concave mirror. It gathers the light from the small bulb and reflects it as a strong, parallel beam, allowing you to see far into the distance.
• Dentist's Mirror: Dentists use a small concave mirror on a handle to get a magnified, erect view of your teeth. By holding the mirror close to a tooth, they can easily spot cavities or other issues that are too small to see directly.
• Reflecting Telescopes: Large, powerful telescopes, like the ones used by astronomers, use a massive concave mirror as their main component to gather faint light from distant stars and galaxies.

{{KEY: type=concept | title=The Power of Concave Reflectors | text=Concave mirrors are excellent at converging light. When a light source is placed at a specific point, the mirror reflects all the light rays into a single, powerful, parallel beam. This property is essential for torches and headlights.}}

Uses of Convex Mirrors

The most important feature of a convex mirror is its ability to give a wide field of view, showing a large area in a small mirror.

• Vehicle Side-View Mirrors: The mirrors on the sides of cars, buses, and motorcycles are convex. They give the driver a wide view of the traffic behind them. The image is smaller, which allows more objects to fit into the reflection. You might have seen the warning: "Objects in the mirror are closer than they appear." This is because the diminished image makes vehicles seem farther away than they are.
• Road Safety Mirrors: At sharp bends or blind intersections on hilly roads, large convex mirrors are installed. They allow drivers to see the traffic coming from around the corner, helping to prevent accidents.
• Security Mirrors: In large stores and supermarkets, you'll often see large, round convex mirrors mounted on the ceiling. These give security personnel a wide-angle view of the aisles to monitor the entire shop and deter theft.

{{VISUAL: diagram: Practical applications of spherical mirrors, showing a cutaway of a torch with a concave reflector, a dentist using a concave mirror, and a convex mirror used as a car's side-view mirror providing a wide field of view.}}

By simply observing the kind of image an object forms, we can distinguish between a plane, concave, or convex mirror without even touching it

What Are the Laws of Reflection? — Part 1

{{FORMULA: expr=∠i = ∠r | symbols=∠i:Angle of Incidence (°), ∠r:Angle of Reflection (°) }}

The Rules of the Game: What Are the Laws of Reflection?

We've seen that mirrors can form images, from the simple reflection in a plane mirror to the wide-angle view in a convex mirror. But how does this happen? Is it random, or does light follow a specific set of rules when it bounces off a surface?

Think of it like bouncing a ball. If you throw it straight down, it bounces straight up. If you throw it at an angle, it bounces off at an angle. Light behaves in a similarly predictable way. Scientists have discovered two simple but powerful laws that govern all reflection, whether from a flat mirror, a curved mirror, or even the surface of a calm lake.

To understand these laws, we first need to learn the language used to describe the path of light.

The Key Players in Reflection

Imagine a single, thin beam of light travelling from a source, like a torch. We represent this path using a straight line with an arrow, called a ray of light. When this ray interacts with a mirror, we can identify three important components.

• Incident Ray: This is the ray of light that travels from the light source and strikes the mirror's surface. Think of it as the "incoming" ray.
• Reflected Ray: After hitting the mirror, the light bounces off. This "outgoing" ray, which travels away from the mirror, is called the reflected ray.
• Normal: This is an imaginary line drawn perpendicular (at a 90° angle) to the surface of the mirror at the exact point where the incident ray strikes. The normal helps us define a reference line to measure angles accurately.

{{VISUAL: diagram: A ray of light reflecting from a plane mirror. The diagram clearly labels the 'Incident Ray' with an arrow pointing towards the mirror, the 'Reflected Ray' with an arrow pointing away, and the 'Normal' as a dashed line perpendicular to the mirror surface at the point of incidence.}}

{{KEY: type=definition | title=Key Terms in Reflection | text=Incident Ray: The light ray striking the surface. Reflected Ray: The light ray bouncing off the surface. Normal: The line perpendicular to the surface at the point of incidence.}}

Measuring the Angles

The laws of reflection are all about the relationship between angles. With our key players defined, we can now measure the two crucial angles involved:

1. Angle of Incidence (∠i): The angle between the incident ray and the normal.
2. Angle of Reflection (∠r): The angle between the reflected ray and the normal.

It's extremely important to remember that both angles are always measured from the normal, not from the surface of the mirror. This is a common point of confusion.

The First Law of Reflection

When you perform an experiment like the one described in your textbook (Activity 10.4), where you shine a ray of light onto a mirror and carefully measure the angles with a protractor, you discover a consistent and beautiful relationship.

No matter what angle you choose for the incoming ray, the outgoing ray will always bounce off at the exact same angle on the other side of the normal.

{{KEY: type=concept | title=The First Law of Reflection | text=The angle of incidence is always equal to the angle of reflection. This is mathematically written as ∠i = ∠r.}}

This means if a light ray strikes a mirror at an angle of 30° to the normal, it will reflect at an angle of 30° to the normal. If the angle of incidence is 60°, the angle of reflection will be 60°.

What if the light hits the mirror straight on? If the incident ray travels along the normal itself, it strikes the mirror at an angle of 90° to the surface. In this case, the angle of incidence (∠i) is 0°. According to the first law, the angle of reflection (∠r) must also be 0°. This means the light ray will bounce straight back along the same path it came from!

The Second Law of Reflection

There's one more rule that light follows. Think about the experiment where you shine a beam of light across a flat sheet of paper towards a mirror (Activity 10.5). You can see the incident ray and the reflected ray clearly on the paper.

Now, what happens if you bend the part of the paper where the reflected ray is? The reflected ray disappears! When you flatten the paper again, it reappears.

{{VISUAL: photo: A side-by-side comparison. Image (a) shows a light ray reflecting on a flat sheet of paper, with the incident and reflected rays both visible. Image (b) shows the paper bent, and the reflected ray is no longer visible on the bent portion.}}

This simple demonstration reveals the second law of reflection. All three key lines—the incident ray, the reflected ray, and the normal at the point of incidence—always lie in the same flat plane. Bending the paper creates a new plane, which is why the reflected ray is no longer visible on it.

{{KEY: type=concept | title=The Second Law of Reflection | text=The incident ray, the normal to the mirror at the point of incidence, and the reflected ray all lie in the same plane.}}

These two laws are fundamental to understanding how all mirrors—plane and spherical—create the images we see.

{{KEY: type=exam | title=Common Trap | text=In questions, you might be given the angle between the incident ray and the mirror surface (called the grazing angle). Remember to first calculate the angle of incidence by subtracting this value from 90° before applying the law ∠i = ∠r.}}

Solved Numericals

The First Law of Reflection is a simple but powerful formula that helps us predict the path of light.

Hero Formula: Angle of Incidence = Angle of Reflection ∠i = ∠r

Example 1 GIVEN: A ray of light strikes a plane mirror such that the angle of incidence is 45°. What is the angle of reflection?

FORMULA: First Law of Reflection: ∠i = ∠r

SUBSTITUTION: Given ∠i = 45° Therefore, ∠r = ∠i ∠r = 45°

ANSWER: The angle of reflection is 45°.

Example 2 GIVEN: A beam of light strikes a plane mirror at an angle of 30° with the mirror surface. Find the angle of reflection.

FORMULA:

1. The angle of incidence is the angle between the incident ray and the normal.
2. The normal is at 90° to the mirror surface.
3. ∠i = 90° – (angle with mirror surface)
4. First Law of Reflection: ∠i = ∠r

SUBSTITUTION: First, find the angle of incidence: ∠i = 90° – 30° ∠i = 60°

Now, apply the First Law of Reflection: ∠r = ∠i ∠r = 60°

ANSWER: The angle of reflection is 60°.

Try It Yourself

1. If the angle of reflection for a ray of light is 72°, what is the angle of incidence?
2. A ray of light is incident normally on a plane mirror. What will be the angle of reflection?
3. The angle between the incident ray and the reflected ray is 100°. What is the angle of incidence?

Answer Key: 1. 72° | 2. 0° | 3. 50°

What Are the Laws of Reflection? — Part 2

{{FORMULA: expr=∠i = ∠r | symbols=∠i:Angle of Incidence (°), ∠r:Angle of Reflection (°)}}

Laws of Reflection in Action: Spherical Mirrors

In the previous section, we established the two fundamental laws of reflection using a plane mirror. A key question arises: Do these laws also apply to curved or spherical mirrors?

The answer is a resounding yes! The laws of reflection are universal and apply to any reflecting surface, regardless of its shape. However, the effect of reflection on a bundle of light rays can be dramatically different depending on the mirror's curvature. Let's explore this using an experiment similar to the one we did before.

Activity: Parallel Rays on Different Mirrors

Imagine instead of a single thin beam of light, we use a comb to create several parallel beams of light. What happens when this "sheet" of light falls on different types of mirrors?

1. On a Plane Mirror

When multiple parallel rays of light strike a plane mirror, they reflect off the surface and remain parallel to each other. The direction of the entire bundle of rays changes, but they do not spread out or come together.

{{VISUAL: diagram: Parallel light rays from a comb hitting a plane mirror and reflecting as a parallel beam, maintaining their distance from each other.}}

2. On a Concave Mirror

Now, let's replace the plane mirror with a concave mirror. When parallel rays of light hit its inwardly curved surface, something fascinating happens. After reflection, all the rays bend inwards and meet at a single, specific point in front of the mirror.

This act of coming together is called convergence, and a concave mirror is therefore also known as a converging mirror.

{{KEY: definition | title=Principal Focus (Concave Mirror) | text=The point in front of a concave mirror where parallel rays of light meet, or converge, after reflection is called the principal focus (F).}}

Think of it this way: at every tiny point on the curved surface, the law ∠i = ∠r is being followed perfectly. But because the surface is continuously curving, the 'normal' at each point is angled differently, directing every reflected ray towards that one common spot.

{{VISUAL: diagram: Parallel light rays hitting a concave mirror and converging to a single point in front of the mirror, labeled as the Principal Focus (F).}}

3. On a Convex Mirror

Finally, what happens with a convex mirror? Its surface bulges outwards. When parallel rays of light strike it, they reflect and spread out in different directions.

This act of spreading out is called divergence, and a convex mirror is also known as a diverging mirror.

The reflected rays themselves never meet. However, if you trace them backwards (as imaginary lines behind the mirror), they appear to originate from a single point. This is a virtual focus because the light rays don't actually pass through it.

{{KEY: concept | title=Real vs. Virtual Focus | text=A concave mirror forms a real focus, where light rays physically converge. This focus can be projected onto a screen. A convex mirror forms a virtual focus, a point from which rays only appear to diverge. It cannot be formed on a screen.}}

This diverging property is why convex mirrors are used as rearview mirrors in cars. They spread the light out, allowing the driver to see a much wider area behind them.

{{VISUAL: diagram: Parallel light rays hitting a convex mirror and diverging. Dotted lines trace the reflected rays back to a single point behind the mirror, labeled as the Virtual Focus (F).}}

Reflection Type Summary

The simple law angle of incidence = angle of reflection governs the complex behaviours of convergence and divergence in all mirrors.

Solved Numericals

The fundamental law governing all reflection problems is the First Law of Reflection.

Hero Formula: Angle of Incidence (∠i) = Angle of Reflection (∠r)

Example 1: A ray of light strikes a plane mirror such that the angle of incidence is 45°. What will be the angle of reflection?

• GIVEN:

  • Angle of incidence, ∠i = 45°

• FORMULA:

  • According to the first law of reflection, ∠i = ∠r

• SUBSTITUTION:

  • ∠r = 45°

• ANSWER:

  • The angle of reflection will be 45°.

Example 2: A laser beam hits a mirror. The angle between the incident ray and the surface of the mirror is 30°. Calculate the angle of reflection.

• GIVEN:

  • Angle between the incident ray and the mirror surface = 30°

• FORMULA:

  • First, we need to find the angle of incidence (∠i). The normal is perpendicular (90°) to the mirror surface.
  • ∠i = 90° - (Angle between incident ray and mirror)
  • Then, use the law of reflection: ∠i = ∠r

• SUBSTITUTION:

  • ∠i = 90° - 30° = 60°
  • Since ∠i = ∠r, we have ∠r = 60°

• ANSWER:

  • The angle of reflection is 60°.

{{KEY: exam | title=Common Trap | text=Students often mistake the angle given with the mirror surface for the angle of incidence. Always remember, the angles of incidence and reflection are measured from the Normal, not from the mirror's surface.}}

Try It Yourself

1. If a light ray is reflected from a mirror with an angle of reflection of 72°, what was its angle of incidence?
2. A torch is shone on a mirror. The angle between the torch beam (incident ray) and the normal is 25°. What will be the angle between the reflected ray and the normal?
3. An incident ray strikes a mirror exactly along the normal. What are the values of the angle of incidence and the angle of reflection?

Answer Key: 1. 72° | 2. 25° | 3. Both angles are 0°

What Is a Lens? & Summary & Quick Revision

What Is a Lens?

We've seen how shiny, curved surfaces like spoons can act as mirrors, forming images by reflecting light. But what happens when light passes through a transparent material with curved surfaces?

Imagine looking at text through a tiny drop of water on a plastic sheet, just like in Activity 10.8. The letters suddenly appear bigger! This simple water drop is acting as a lens. It bends the light passing through it, changing how we see the object on the other side.

{{KEY: type=definition | title=Lens | text=A lens is a piece of transparent material, like glass or plastic, that has at least one curved surface. Lenses work by refracting (bending) light that passes through them.}}

Unlike mirrors which reflect light, lenses refract light. This is why we look through a lens to see an object, but look at a mirror to see an image.

Types of Lenses

Just like spherical mirrors, lenses come in two main types based on their shape: Convex and Concave.

1. Convex Lens

A convex lens is a lens that is thicker in the middle and thinner at the edges. Think of it as two curved surfaces bulging outwards.

• When you hold a convex lens, it feels fatter in the center.
• The most common example is a magnifying glass.
• In diagrams, it's represented by a straight line with outward-pointing arrows at the ends.

{{KEY: type=points | title=Properties of a Convex Lens | text=- Thicker at the center and thinner at the edges.

• Known as a converging lens because it brings parallel rays of light together.
• Can form both real, inverted images and virtual, erect images depending on the object's distance.}}

2. Concave Lens

A concave lens is the opposite. It is thinner in the middle and thicker at the edges. It looks like it's been "caved in" from both sides.

• When you hold a concave lens, you'll feel the thicker edges and the thin center.
• These are used in eyeglasses to correct nearsightedness.
• In diagrams, it's represented by a straight line with inward-pointing "forks" at the ends.

{{VISUAL: diagram: Comparison of a convex lens (thicker middle) and a concave lens (thinner middle), with their respective schematic symbols used in ray diagrams.}}

Converging vs. Diverging Action

Lenses have a powerful effect on parallel beams of light.

• Convex Lens (Converging): When parallel rays of light pass through a convex lens, they are bent inwards and meet at a single point. This action of bringing light rays together is called convergence. Hence, a convex lens is also called a converging lens. This is why a magnifying glass can focus sunlight to a tiny, hot point and burn paper!

• Concave Lens (Diverging): When parallel rays of light pass through a concave lens, they are bent outwards and spread apart. This action of spreading light out is called divergence. Therefore, a concave lens is also called a diverging lens.

{{VISUAL: diagram: Ray diagrams showing how parallel beams of light behave after passing through a convex lens (converging to a point) versus a concave lens (diverging away).}}

Images Formed by Lenses

The image you see through a lens depends on the type of lens and how far the object is from it.

{{KEY: type=exam | title=Remembering Lens Images | text=For exams, a simple trick is to remember that a concave lens always forms a diminished, erect, and virtual image, just like a convex mirror. A convex lens, however, behaves much like a concave mirror, capable of forming various types of images.}}

Where Are Lenses Used?

Lenses are all around us, playing a crucial role in science, technology, and our daily lives.

• Eyeglasses: People wear glasses with convex or concave lenses to correct vision problems.
• Cameras: A lens focuses light from the scene onto the sensor to capture a photograph.
• Microscopes & Telescopes: Combinations of lenses are used to see extremely small objects (microscopes) or very distant objects (telescopes).
• Human Eye: Your eye has a natural, flexible convex lens that focuses light onto the retina, allowing you to see!

Chapter Summary: Light

This chapter took us on a journey to understand the fascinating properties of light and how it interacts with different surfaces. Let's recap the main ideas.

Key Principles of Light

• Light travels in straight lines.
• Reflection is the bouncing back of light from a surface. It can be regular (from smooth surfaces like mirrors) or diffused (from rough surfaces).
• The laws of reflection state that the angle of incidence equals the angle of reflection (∠i = ∠r), and all three (incident ray, reflected ray, normal) lie in the same plane.

Mirrors and Their Images

• Plane Mirrors: Form images that are virtual, erect, laterally inverted, same size as the object, and located at the same distance behind the mirror as the object is in front.
• Spherical Mirrors: Are curved mirrors.
  • Concave Mirror (Converging): Curved inwards. Can form real, inverted images or a virtual, erect, and magnified image depending on the object's position. Used by dentists and in car headlights.
  • Convex Mirror (Diverging): Curved outwards. Always forms a virtual, erect, and diminished image. Used as rear-view mirrors in vehicles.

Lenses and Refraction

• Refraction is the bending of light as it passes from one transparent medium to another.
• Lenses are transparent materials with curved surfaces that form images by refracting light.
  • Convex Lens (Converging): Thicker in the middle. Can form real, inverted images or a virtual, erect, and magnified image. Used in magnifying glasses and cameras.
  • Concave Lens (Diverging): Thinner in the middle. Always forms a virtual, erect, and diminished image. Used in eyeglasses for nearsightedness.

The Spectrum of Light

• Sunlight, which appears white, is actually composed of seven colours (VIBGYOR).
• The splitting of white light into its constituent colours is called dispersion. This phenomenon is responsible for the formation of a rainbow.

Light creates the world we see. By understanding mirrors and lenses, we learn how to control light to see things far beyond the limits of our own eyes.